1. Field of the Invention
The present invention relates to an iron core and an electromagnetic driving mechanism employing the iron core. More particularly, the present invention relates to an iron core employed in, for instance, an electromagnetic oscillating type pump of diaphragm type or piston type, and an electromagnetic driving mechanism employing the iron core, which can improve the thrust of an oscillator disposed between electromagnets disposed in an opposing manner.
2. Description of the Related Art
Electromagnetic type pumps are conventionally used mainly for supplying oxygen to fish-farming aquariums or purifying tanks for domestic use and for sampling gas for inspection to observe pollution. Such a pump comprises, as shown, for example, in FIG. 23, electromagnets 101 disposed in an opposing manner, an oscillator 103 having permanent magnets 102, diaphragms 104 coupled to both ends of the oscillator 103, pump casings 105 fixed at both ends of the electromagnets 101, and a pump compressing chamber 106 formed between the diaphragm 104 and the pump casing 105. Each of the electromagnets 101 is finished by assembling a wound coil 108 in an E-shaped iron core 107, and the oscillator 103 is disposed in an air gap 109 formed between the iron cores 107.
In such a pump, oscillation of the oscillator 103 which is supported by the diaphragms 104 causes an increase/decrease in a capacity of the pump compressing chamber 106 in a deflective manner on the right and left, whereby suction and discharge of air is alternately performed on the right and left.
In a conventional pump, thrust in right and left directions F1, F2 of the oscillator 103 can be achieved by suction force between a pole portion 110a of a side pole 110 of each iron core 107 and the permanent magnet 102 as well as that between a pole portion 111a of a center pole 111 and the permanent magnet 102, as shown in FIG. 24 and in FIG. 25.
At this time, there are respectively generated on a magnetic field formed between the iron cores 107 and the permanent magnets 102 a magnetic path A of a closed-circuit type which is formed by the side pole 110, center pole 111 outer yoke 112 and permanent magnets 102 and a magnetic path B of closed-circuit type which is formed by the center pole 111 and permanent magnets 102.
However, the magnetic path B presents a drawback in that it limits the thrust of the oscillator because it causes short-circuiting of magnetic flux of the permanent magnets 102.
In accordance with the present invention, there is provided an iron core comprising an outer yoke, side poles disposed on both end portions of the outer yoke, and a center pole disposed between the side poles, wherein a magnetic path of pole portions of the center pole is formed as an open-circuit.
The center pole is preferably formed of a pair of magnetic poles which are separated from each other by a specified distance.
In accordance with the present invention, there is further provided an electromagnetic driving mechanism comprising electromagnets each composed of the iron core and a winding coil which is wound around pole portions of the iron core, and an oscillator with a pair of permanent magnets disposed in an air gap within the electromagnets and separated from each other by a specified distance, wherein outer shape of the pair of permanent magnets which are directly attached to a shaft assume a square or circular shape, and a polarity of the pair of permanent magnets in a peripheral direction is magnetized to be an anisotropic magnetic pole.